Automatic thread cutting attachment for industrial sewing machines



Dec. 31, 1968 w. R. FOWLER 1 AUTOMATIC THREAD CUTTING ATTACHMENT FOR INDUSTRIAL SEWING MACHINES Filed May 19, 1967 INVENTOR WILB RN R. FOWLER AT" NEY United States Patent F 3,418,953 AUTOMATIC THREAD CUTTING ATTACHMENT FOR INDUSTRIAL SEWING MACHINES Wilburn R. Fowler, 2211 E. 35th St., Chattanooga, Tenn. 37407 Filed May 19, 1967, Ser. No. 639,688 Claims. (-Cl. 112252) ABSTRACT OF THE DISCLOSURE An automatic thread cutter for attachment to and adapted to be driven by the feed dog activating bar of an industrial sewing machine. A bracket is attached to the feed dog activating bar, from which it receives reciprocating horizontal motion. A lever pivotally attached between its ends to a housing is reciprocated at one end by a bearing on the bracket and its other end actuates the movable blade of the cutter. A vacuum tube draws the thread to be cut into the cutter and removes from its vicinity waste thread and lint.

Background 0 the invention In the hosiery industry, one method used to close the toe of a stocking or a sock is to sew it on an industrial type sewing machine used in the manufacture of clothing. This machine produces a chain stitch which neatly closes the toe of the sock.

In continuous operation of the sewing machine, the chain stitch of thread carries over from one sock to the next and the operator must stop periodically to separate the socks by cutting the stitches. The time spent in cutting the stitches reduces the efiiciency of the entire operation by stopping the continuous flow of work through the machine.

Another method of cutting the thread between garments or hose employs a small burner. This method is limited solely to nylon thread and the use of a burner has been known to cause fires, resulting in the total loss of a factory.

The hosiery industry has been searching for many years for a means of cutting the chain stitches eificiently, but none of the devices developed so far has been accurate or compact enough to work satisfactorily.

Brief description of the drawing FIG. 1 is a top plan view of a main bracket which is connected to the feed dog activating bar of a sewing machine, not shown;

FIG. 2 is a front elevation of the bracket shown in FIG. 1;

FIG. 3 is a top plan view of a cutter mechanism which is connected to and driven by the bracket shown in FIGS. 1 and 2;

FIG. 4 is a front elevation;

FIG. 5 is a side elevation; and

FIG. 6 is a bottom plan view of the cutter mechanism shown in FIG. 3.

Description of the preferred embodiment The device consists of two primary assemblies as shown in the drawings.

The assembly generally indicated at 1 is a main bracket, which activates the cutter mechanism. It is attached to and is driven by the feed dog activating bar of a sewing machine, not shown, by a single bolt fastened through a hole 2.

The feed dog of a sewing machine is a small, sawtoothed, mechanism, not shown, located on both sides of the needle hole in the baseplate, or work platform, of the machine. The feed dog moves in a forward and back- Patented Dec. 31, 1968 ward motion to feed the garment through the machine. An opening 3 is provided in the main bracket to give access to the cams which operate the machine, for maintenance purposes and to change the type or size of stitches being made on the machine. A double arrow in the opening 3 shows the direction of reciprocating transverse movement of the entire assembly 1.

A bracket 4 is provided for adjusting the timing of the opening and closing of the cutter knives, described hereinafter. Adjustment of the bracket 4 is provided by screws 5. A ball bearing 6 is fixed to the bracket 4. An opening 7 is provided for oiling the sewing machine cams and mechanism without removing the automatic thread cutting attachment.

The cutter mechanism generally indicated at 10 includes a main body or housing 11, attached to the sewing machine by a bolt inserted through a slotted opening 12. The opening 12 provides for adjusting the cutting mechanism to cut closer to or farther from the work, such as stockings. A lever 13 is attached to a ball bearing 14 mounted on an arm 15 of the cutting mechanism. A socket 16 of the lever 13 fits over the bearing 6 on the main bracket 1; thus, the direction of movement of the lower end of the lever 13 at the socket 16 is the same as that of the main bracket 1. A forked opening 17 in the top of the lever 13 straddles an extension 18 on a moving cutter blade 19. The moving blade 19 pivots on a bolt 20 when pushed by the lever 13, and works in conjunction with a fixed blade 21 to cut the chain stitch produced by the sewing machine. The fixed blade 21 is attached to the housing 11 by bolts 22 and 23. A leaf spring 24 and a coil spring 25 provide the exact balance of tension on the cutting blades for maximum cutting etficiency with minimum wear.

A vacuum tube 26 draws the thread from the sewing machine into an opening or groove 27 of the housing 11 and consequently into the cutting blades. It also removes all cut chain-stitch particles and lint from this area of the machine, further speeding the work and reducing maintenance.

The main bracket 1, the housing 11 and the lever 13 constructed of aluminum or other lightweight metal to provide for minimum loading of the sewing machine to which they attach. The cutting blades 19 and 21 are fabricated of the highest grade of steel.

In operation, the feed dog activating bar of the sewing machine moves forward and backward and, by the bolt fastened through hole 2, carries with it the bracket 1. The bearing 6 engages the socket 16 and reciprocates the lever 13 on its bearing 14, thereby actuating through the forked opening 17 the extension 18 and the moving cutter blade 19 to sever the chain stitch of thread between garments. The vacuum tube 26 draws the connecting thread into the cutter and removes waste thread and lint.

It will be evident to those skilled in the art that this automatic cutting mechanism would not be limited solely to the hosiery industry in which it was developed but could be applied throughout the garment industry where mass production methods are used.

This invention is an automatic thread cutter consisting of a compact mechanism which attaches to, and becomes an integral part of, a sewing machine. The thread cutter does not protrude from the machine in any way that will hinder the normal sewing operation of the machine. The simple scissor-type cutter mechanism provided in this invention works equally well on all types of thread (cotton, nylon, etc.) without complicated changes or adjustments.

I claim:

1. In an automatic thread cutter for attachment to and adapted to be driven by a sewing machine having a reciprocating feed dog activating bar, the improvement comprising a bracket attached to the feed dog activating bar, a bearing fixed to the bracket, a housing attached to the machine, a lever pivotally attached to the housing and actuated by the bearing, said lever having an opening therein remote from said bearing, a cutter forming part of and attached to the housing including a fixed blade and a movable blade, said opening in said lever straddling a portion of said movable blade, the movable blade being pivoted on the housing and actuated in succession by the lever, the bearing, the bracket and reciprocal movement of the feed dog actuating bar, and means for drawing thread to be cut into the cutter.

2. The device according to claim 1 in which the bracket is adjustable relative to the machine to vary the timing of the cutter.

3. The device according to claim 1 in which the housing is adjustable relative to the machine to vary the distance of the cutter from the material being sewn on the machine.

4. The device according to claim 1 in which the lever is pivoted between its ends closer to the bearing than the cutter.

5. The device according to claim 1 in which the means for drawing thread to be cut into the cutter is a vacuum tube.

References Cited UNITED STATES PATENTS 1,010,830 12/1911 Weis 112252 1,315,064 9/1919 Williams l12-252 X 2,168,276 8/1939 Weis 112-252 X 3,242,892 3/1966 Fowler 112252 HERBERT F. ROSS, Primaly Examiner. 

